Whip-stitching attachment for sewing machines



June 20, 1939. T. E. D. BILDE WHIP-STITCHING ATTACHMENT FOR SEWING MACHINES Filed Oct. 28, 1936 W I z 197' 1/ w 1 '6 50 Patented June 20, 1939 PATENT OFFICE WHIP-STITCHING ATTACHMENT FOR SEWING MACHINES Tord Erik Daniel Bilde, Stockholm, Sweden Application October 28, 1936, Serial No. 108,072 In Sweden November 2, 1935 4 Claims. 01. 112-162) The present invention relates to devices for whip-stitching borders of fabrics which devices derive their movement from a movable member of a sewing machine and, preferably, operate wholly above the sewing machine table, said devices forming a whip-stitching seam in such manner that a separate over-casting thread is carried alternately on opposite sides of the fabric in front of the needle of the sewing machine by means of a thread guide, said thread forming loops alternately on opposite sides of and then around the border of the fabric. For this purpose the thread guide must change its position in relation to the border of the fabric.

The invention is characterized by the fact that the thread guide for the over-casting thread is brought to describe the path of movement required for the whip-stitching operation by a guiding means, preferably formed as a twobranched path.

The invention is further characterized by the fact that the device may be arranged detachably in such manner that it may be clamped between the frame arm of the sewing machine and the table.

The invention is illustrated on the accompanying drawing, in which:-

Fig. 1 is a lateral View of a device according to the invention having the needle bar rockable about a point at the lowermost end of the bell crank lever.

Figs. 2 and 3 show sectional details of two embodiments of the guiding means.

Fig. 4 is a View of reversing means for actuating the end of the needle bar.

In the drawing ll designates the frame arm of the sewing machine, l2 the needle bar, l3 the needle and M the needle carrier provided with a threaded hole l5 for receiving the end of a clamping screw 34. I6 designates the machine table, IT a plate for lifting up the fabric I8, IS the bed plate of the device, 20 one side wall thereof and 2| the intermediate portion between the side walls. 23 is a projection extending into a hole in the sewing machine table and 24 is a friction plate. 25 designates a sleeve having internal threads and secured tothe top of the device and 26 is a screw engaging said sleeve and having a pointed end 2! which is screwed against the sewing machine frame arm I l thereby clamping the device against the sewing machine table. 29 designates a bell crank lever pivoted on a pin 30. At its one end the lever 29 is, by means of ball joints 3|, 32 and an arm 33, movably connected with a screw 34 adapted to be screwed into the threaded hole which commonly serves to receive the clamping screw for the sewing machine needle l3. At its other end the screw 34 forms the ball of the ball joint 32 so as to be capable of turning about its longitudinal axis. Preferably, the rotation. of the screw 34 may" be effected by a pin inserted in a hole 35v insame. Further the screw is preferably provided with locking means, such as a locking nut 3411, as seen in the drawing. The bar 31 is swingable up and down on a shaft 36 at the lower end of the bell crank lever 29. Preferably, the needle bar 31 as well as the bell crank lever 29 are made of flat material.-

The bar 31 is provided with a carrier 38 for an overcasting needle 39. Secured to the bar 3! in the immediate vicinity of the carrier 38 is a guiding pin 42 engaging the curved recess in the guide member 43. At the end of the bar 31 remote from the needle and at the other side of the pivot 36 said bar is provided with tworecesses 44, 45 on opposite sides of an edge 46. These recesses 44 and 45 are adapted to be engaged alternately by the pointed end portion which is carried by a spring 41. 49 designates a carrier for the thread reel and 50 a spring for tensioning the over-casting thread. From the loop 48 of the spring 50 the thread 4| passes through a slot 5| in the upper surface of the device to the overcasting needle 39.

Figs. 2 and 3 show different embodiments of the guiding means 43 on an enlarged scale, the curve having a semicircular end bend for the reversion of the bar 31 into its two positions of height without using any reversing means, the

curve branches being separated by an intermediate portion 54.

As shown in Fig. 4 the spring 41 is secured to a member 51in. the line about which the bar is swinging. Thus, the edge 46 will lie alternately above and below the point 10 of the spring 41 so as to cause the recesses 44 and 45 to be engaged alternately.

position the guiding pin 42 lies in the bend of the guiding means.

When the guide means shown in the drawing is used the overcasting needle 39 in returning from a position along the upper side of a cloth 3 will cause the guide pin 42 to finally engage the curved end portion of the track 43a. The bar 31 then starts turning about the shaft 36 and the end portion having the recesses 44 and 45 will be moved upwards and the pointed end portion ID of the spring will move over the edge 46 into the recess 45. Such a movement of the spring will take place when the pin 42 reaches a position opposite the pointed end of the intermediate portion 54. The spring 4'! is also compressed during the retraction of the overcasting needle 39 and the left hand portion of the bar 31 will be urged downwardly after the end portion of the spring engages the recess 45. Thus the guide pin 42 will be caused to move along the lower branch of the track 43a when the bellcrank lever 29 moves the bar 31 towards the cloth. The overcasting needle therefore will pass along the underside of the cloth l8. During the return movement of the overcasting needle from the underside of the cloth the left hand end portion of the bar 31 is urged into the upper branch of the track 43a by means of the guide pin 42 and the spring 41 cooperating with the recess 44.

What I claim is:

1. An appliance for attachment to a sewing machine for the formation of a whip-stitching seam, comprising a movable thread guide for an over-casting thread, means adapted to be coupled to a movable part of the machine to transmit motion therefrom to said thread guide, fixed guiding means for said thread guide forming two guiding paths substantially parallel to the direction of the movement of the thread guide to cause same to describe a movement above and below the fabric to be over-cast to form a whipstitching seam together with the conventional two threads of the sewing machine.

2. An appliance for attachment to a sewing machine for the formation of a whip-stitching seam, comprising a movable thread guide for an over-casting thread, means adapted to be coupled to a movable part of the machine to transmit motion therefrom to said thread guide, fixed guiding means for said guide forming two guiding paths displaced vertically to each other, and reversing means to guide the thread guide from one path to the other to cause same to describe a movement above and below the fabric to be over-cast to form a whip-stitching seam together with the two conventional threads of the sewing machine.

3. An appliance for attachment to a sewing machine for the formation of a whip-stitching seam, comprising a bell crank lever, a thread guide for an over-casting thread rockably mounted on said lever, means adapted to be coupled to a movable part of the machine to transmit motion therefrom to said bell crank lever, and fixed means for said thread guide forming two guide paths substantially parallel to the direction of the movement of the thread guide to cause same to describe a movement above and below the fabric to be over-cast to form a whipstitching seam together with the two conventional threads of the sewing machine.

4. An appliance for attachment toa sewing machine for the formation of a whip-stitching seam, comprising a bell crank lever, a thread guide for an over-casting thread rockably mounted on said lever, means adapted to be coupled to a movable part of the machine to transmit therefrom motion to said lever, and fixed means for said guide forming two paths displaced vertically to each other to cause the thread guide under the action of said motion means to describe a movement above and below the fabric to be over-cast to form a whip-stitching seam together with the conventional two threads of the sewing machine.

TORD ERIK DANIEL BILDE. 

